a. Field of the Invention
This invention relates to a fluid delivery apparatus for use in a medical setting which operates as a closed pressurized system incorporating a dual check valve and waste container and which facilitates positive flow delivery of fluids to a patient while helping prevent the accidental injection of air.
b. Description of the Prior Art
In the medical setting, and primarily in angiography, avoiding the accidental injection of air into a patient's vascular system is of great importance. The injection of an air bubble into a vein or artery while administering fluid can result in severe medical complications and even death.
Prior art fluid delivery systems that aspirate fluid from a reservoir by vacuum increase the risk for accidental injection of air into a patient because as fluid is vacuum drawn for subsequent injection into a patient, there is a risk that, in addition to the fluid, gas from suspension in the fluid can be drawn. This drawn gas can be introduced into the vascular system with the fluid upon injection.
Pressurized systems aid in avoiding the accidental injection of air associated with vacuum aspirated systems. With a pressurized system, fluid is forced under pressure into the syringe of the fluid delivery apparatus, and the potential for drawing gas from suspension is eliminated. However, the potential for injection of contaminants and gases may still exist with a pressurized system unless that system remains closed at all times during a fluid delivery procedure. A risk that air could accidently enter the system and be directed toward the patient is presented each time some part of the system is opened.
Pressurized fluid delivery systems are useful for delivering saline and contrast media in cardiac catheterization procedures. Although, ideally, such fluid delivery systems should remain closed, typical prior art pressurized systems are opened during normal use. In catheterization procedures a catheter is aspirated and flushed after it has been inserted into a patient. This involves the aspiration of blood from the patient. Aspirated blood and air must be discarded prior to the introduction of saline and contrast media. In systems without a waste component, the apparatus needs to be disconnected to eliminate this waste. In so doing, the system is opened to the environment, risking both the further introduction of air or other contaminants as well as physician contact with body fluids.
It may be desirable to view several locations in a patient's vascular system during a single catheterization procedure. This may require the use of different specially designed catheters to facilitate access to each location within the vascular system. Thus, catheters will be disconnected and replaced during a single procedure. Each time a new catheter is inserted, it must be connected to the fluid delivery apparatus, aspirated and flushed. The aspirated blood and air need to be discarded each time. Without a waste component in the system, the apparatus is disconnected to externally dispel waste. The risk of the introduction of air therefore may be increased with modern cardiac catheterization procedures, for example, because the need and practice of using different catheters during a single procedure causes the system to be repeatedly opened to the environment.